Article of manufacture

ABSTRACT

A caster for chairs has a circular hub through which an axle extends centrally with end portions projecting beyond opposite axial sides thereof. A pair of rollers are each journalled on one of these end portions and the hub is provided with a socket by means of which it can be mounted for pivoting movement about an upright axis which is laterally offset from and extends normal to the axle. A nose projects from the outer circumferential face of the hub below the socket and is bounded by two outer surfaces which extend from the outer circumferential face substantially parallel to and circumferentially normal to the axis, respectively.

United States Patent [191 Bocksch et al.

ARTICLE OF MANUFACTURE Inventors: Karl Bocksch, Arolsen; Willi Hensel,

Willingen, both of Germany Mauser Kommanditgesellschaft, Koeln, GermanyFiled: Dec. 29, 1972 Appl. No.: 319,768

Assignee:

Foreign Application Priority Data Jan. 3, 1972 Germany 2200062References Cited UNITED STATES PATENTS 11/1933 Wilson ..16/18 A 12/1950Schultz 16/18 GG [111 3,805,320 [451 Apr. 23, 1974 3,719,370 3/1973Gintick 16/18GG 2,423,659 7/1947 Rabe 297/310 Primary Examiner-Bobby R.Gay Assistant Examiner-Doris L. Troutman Attorney, Agent, or FirmMichaelS. Striker [57] ABSTRACT A caster for chairs has a circular hub throughwhich an axle extends centrally with end portions projecting beyondopposite axial sides thereof. A pair of rollers are each journalled onone of these end portions and the hub is provided with a socket by meansof which it can be mounted for pivoting movement about an upright axiswhich is laterally offset from and extends normal to the axle. A noseprojects from the outer circumferential face of the hub below the socketand is bounded by two outer surfaces which extend from the outercircumferential face substantially parallel to and circumferentiallynormal to the axis, respectively.

6 Claims, 4 Drawing Figures PATENTEU APR 23 I974,

ARTICLE OF MANUFACTURE BACKGROUND OF THE INVENTION The present inventionrelates generally to articles of manufacture, and more particularly to acaster for chairs and the like.

Casters are already well known in many different types and uses. Thepresent invention is particularly concerned with casters which areemployed on chairs and similar seating-type furniture and wherein acircular hub is provided with an axially extending axle on opposite endportions of which are journalled rollers for rotation relative to thehub. The hub itself is provided with a socket in which a pin mounted onthe piece of furniture can be received, so that the hub can pivot aboutan axis which is laterally offset from and extends normal to the axle onwhich the rollers rotate. Usually, chairs and similar types of furniturewhich are provided with casters have bases of usually cruciform-shapedconfiguration. The three or more arms or projections of such bases areeach provided with a caster. The difficulty with the prior art is thatwith the particular type of casters with which the present invention isconcerned, even a small tilting of the piece of furniture while load isapplied to it tends to cause the piece of furniture to roll rearwardlyand to fall over forwardly. It is very common in chairs using casters,particularly office chairs, to provide bases having only three legs, orhaving legs which are relatively short. On the one hand the shortness ofthe legs in particular is desirable, because it is space saving andreduces the danger that someone walking past the piece of furnituremight get his or her feet hooked underneath the base and become tripped.On the other hand, however, this type of base brings with it aparticular danger that the chair or furniture might overturn under theconditions outlined above, and the possibility of trouble is furtherenhanced if the person resting on the chair or piece of furniture placesweight upon the region as to the front of the seat and thus shifts thecenter of gravity too far forwardly.

It has been observed that in the stability or instability of suchfurniture the position of the rollers of the casters in the regionswhere the caster pivots about the upright pivot axis thereof, isparticularly important. If the caster is so positioned that its axleabout which its rollers rotate, extends in direction outwardly towardsthe end of the base projection on which the caster is mounted, then thedanger that the chair might tilt over under the above-outlinedcircumstances is reduced or eliminated, because this in effect causes anincrease in the critical rolling-inclination angle that leads totiltingover. If, however, the axle is oriented in the direction towardsthe center of the base, then the chair will tip forwardly about theaxle, and will then slide rearwardly on the forwardly located castersuntil a sufficient shifting in the center of gravity has taken place forthe chair to tilt over in forward direction. The same is true in thereverse case, if the chair is tilted rearwardly.

Investigations have indicated that this particular problem is foundquite frequently in chairs having casters, particularly office chairs,and that it rather often leads to physical injuries which may range fromlight all the way to quite severe.

SUMMARY OF THE INVENTION It is, accordingly, a general object of thepresent invention to provide an improved caster for chairs and the like,which is not possessed of the aforementioned disadvantages of the priorart.

More particularly it is an object of the present invention to providesuch an improved caster which will provide for automatic blocking in thecritical tilting range of the casters, so as to prevent a rearwardrolling of the casters in the event of a tilting-over movement of thepiece of furniture and an unfavorable distribution of the weight of theuser on the seat.

An additional object of the invention is to provide such a caster whichshould be uncomplicated in its construction and simple to produce.

In keeping with these objects, and others which will become apparenthereafter, one feature of the inven tion resides, as a novel article ofmanufacture, in a caster for chairs and the like which, briefly stated,comprises a circular hub having an outer circumferential face, and anaxle extending centrally through this hub and having end portionsprojecting beyond opposite axial sides thereof. A pair of rollers islocated at the opposite axial sides of the hub and each of these isturnably journalled on one of the end portions. Mounting means isprovided for mounting the hub turnably about an upright pivot axis whichis laterally offset from it extends normal 'to the axle, and a noseprojects from the outer circumferential face of the hub below themounting means and is bounded by two outer surfaces which extend fromthe outer circumferential face substantially parallel to andsubstantially normal to the axis, respectively.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a section taken on line I-lof FIG. 4;

FIG. 2 is a side view illustrating the hub of the embodiment shown inFIGS. 1 and 41;

FIG. 3 is a view of the hub in FIG. 2, as seen in the direction of thearrow III shown in FIG. 4; and

FIG. 4 is a side view of the embodiment of the caster in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the embodiment inFIGS. 14 it will be noted that FIGS. 1 and 4 illustrate the completecaster whereas FIGS. 2 and 3 are views of the hub of the caster. .Withthis in mind it is pointed out that the hub itself is completelycircular in outline and is identified with reference numeral 1. Securedin it, as by casting the huh 1 around it, isan axle 2 opposite axialends of which project beyond the opposite axial sides of the hub 1.

Also located at the opposite axial sides of the hub l are two rollers 4which are of cupped configuration as shown, their open sides facinginwardly towards the hub 1. The rollers 4 are each journalled on one ofthe projecting end portions of the axle 2, for which purpose the rollers4 are provided with bores or recesses accommodating journal sleeves 8 inwhich the end portions of the shaft 2 are received. Outwardly springycirclips 3 (that is circumferentially incomplete spring-metal ringswhich, when radially inwardly defected, tend to resume theirlarge-diameter original dimensions) secure the rollers 4 on the endportions of the axle 2 in known manner. Usually this is done by havingcorresponding grooves in the outer surface of the respective end portionand in the inner surface of the respective journalled sleeve 8, with thecirclips being received in part in the respective groove.

The rollers 4 in the illustrated embodiment have outer circular flanges10 the outer surface of which contact the support surface for thecasters, for instance a floor. The inner surfaces of these flanges 10are slightly spaced from the outer circumferential face bounding thecircular hub 1, and they extend partly in axial direction over thisouter circumferential face. However, the flanges 10 define with oneanother an axial circumferentially extending gap, that is they do notcontact one another.

The hub 1 is provided with mounting means for mounting it turnably aboutan upright pivot axis which is laterally offset from and extends normalto the axle 2. In the illustrated embodiment this mounting means is inform of a bore or socket 9 which can receive a downwardly projecting pinprovided in the piece of furniture to which the caster is to be secured.Of course, it is conceivable that the pin might form a part of the hubitself, rather than be an extraneous component which is receivable inthe socket 9. In any case, how- .ever, the axis about which the hub 1will thus be pivotable will be laterally spaced from the axle 2 (seeFIG. 2), will have an upright orientation and will extend normal to theaxle 2.

FIGS. 2-4 indicate particularly clearly that there is located. beneaththe socket 9 a nose 5 bounded by a surface 6 which extends insubstantial parallelism with the pivot axis passing longitudinallythrough the center of the socket 9, and by a second surface 7 whichextends normal to this pivot axis, that is in substantial parallelismwith the surface on which the caster is to be supported. In theillustrated embodiment the two surfaces 6 and 7 include with one anotheran obtuse angle and each of the surfaces merges tangentially into theouter circumferential face of the hub 1. Of course, it is conceivable tohave the surfaces 6 and 7 include a different angle, for instance theycould include a right angle with one another.

Because the flanges 10 partly overlap the circumferential face of thehub 1 in the illustrated embodiment, the axial thickness of the nose 5is less than the axial length of the outer circumferential face, and inparticular it is less than the axial width of the gap defined betweenthe juxtaposed edges of the flanges 10 (compare FIGS. 1 and 3).

With a caster constructed as disclosed herein, the problem which is soobjectionable in the prior art has been overcome. If in the criticalpivotal position of the caster on the chair the latter tilts, then thenose of the respective caster will contact the ground and will preventthe rearward rolling-away of the chair.

If, as has been shown in the illustrated embodiment, the flanges l0partially overlap the outer circumferential face of the circular hub lin the illustrated manner,

then the entry of contaminants, particularly of carpet threads whichmight have become severed from the carpet, into the interior of thecaster and to the axle 2 thereof, is at least made more difficult whichof course is beneficial in terms of continued maintenance-free andreliable operation.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in acaster for chairs and the like, it is not intended to be limited to thedetails shown, since various modifications and structural changes may bemade without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. As a novel article of manufacture, a caster for chairs and the like,comprising a circular hub having an outer circumferential face; an axleextending centrally through said hub and having end portions projectingbeyond opposite axial sides thereof; a pair of rollers located at saidopposite axial sides of said hub and each being turnably journalled onone of said end portions; mounting means for mounting said hub turnablyabout an upright pivot axis which is laterally offset from and extendsnormal to said axle; and a nose projecting from the outercircumferential face of said hub below said mounting means and beingbounded by two outer surfaces which extend from said outercircumferential face substantially parallel to and substantially normalto said axis, respectively.

2. An article of manufacture as defined in claim 1, wherein saidsurfaces include with one another an acute angle.

3. An article of manufacture as defined in claim 1, wherein the diameterof said rollers is greater than that of said hub.

4. An article of manufacture as defined in claim 1, wherein said rollershave respective outer circumferential circular flanges which slightlyoverlap said outer circumferential face in direction axially of said hubbut are radially outwardly spaced from said circumferential face, theflanges of said rollers defining between themselves a gap extendingcircumferentially of said face; and wherein said nose has a thickness inaxial direction of said hub and said gap which is smaller than the axialdimension of said gap.

5. An article of manufacture as defined in claim 1, wherein said hub andnose are of one piece with one another.

6. An article of manufacture as defined in claim 1, wherein saidmounting means comprises an elongated socket whose central longitudinalaxis coincides with

1. As a novel article of manufacture, a caster for chairs and the like,comprising a circular hub having an outer circumferential face; an axleextending centrally through said hub and having end portions projectingbeyond opposite axial sides thereof; a pair of rollers located at saidopposite axial sides of said hub and each being turnably journalled onone of said end portions; mounting means for mounting said hub turnablyabout an upright pivot axis which is laterally offset from and extendsnormal to said axle; and a nose projecting from the outercircumferential face of said hub below said mounting means and beingbounded by two outer surfaces which extend from said outercircumferential face substantially parallel to and substantially normalto said axis, respectively.
 2. An article of manufacture as defined inclaim 1, wherein said surfaces include with one another an acute angle.3. An article of manufacture as defined in claim 1, wherein the diameterof said rollers is greater than that of said hub.
 4. An article ofmanufacture as defined in claim 1, wherein said rollers have respectiveouter circumferential circular flanges which slightly overlap said outercircumferential face in direction axially of said hub but are radiallyoutwardly spaced from said circumferential face, the flanges of saidrollers defining between themselves a gap extending circumferentially ofsaid face; and wherein said nose has a thickness in axial direction ofsaid hub and said gap which is smaller than the axial dimension of saidgap.
 5. An article of manufacture as defined in claim 1, wherein saidhub and nose are of one piece with one another.
 6. An article ofmanufacture as defined in claim 1, wherein said mounting means comprisesan elongated socket whose central longitudinal axis coincides with saidpivot axis.